Microbiota characterization following neonatal permethrin exposure: effect of alkaline water

Objectives: Microbiota is important in supplying nutrients and vitamins, giving colonization resistance against pathogenic bacteria and interacting with the host immune system and intestinal epithelium. The intestinal microbial colonization is essential for the maturation of immune system and for the developmental regulation of the intestinal physiology. Alterations in the colonization process predispose and increase the risk to disease later in life. This study aims to understand if the pesticide permethrin (PERM) administered to rats in early age can affect later the microbiota composition and the effect of alkaline water. The bacterial strains selected as reference strains for the quantification of the target species included Bacteroides fragilis DSM 2151, Staphylococcus aureus ATCC 29213, Blautia producta DSM 2950, Lactobacillus acidophilus ATCC 314, Bifidobacterium longum DSM 20219, Escherichia coli ATCC 25288. The relative content of short chain free fatty acids (SCFFAs) acetic, propionic and butyric, found in the faecal content, was also monitored. Methods: PERM was administered orally to Wistar rats from PND6 to PND21. The faecal samples were collected after 3 days, 1 month and 2 months stopping the treatment from each rat (PERM treated and control groups; PERM treated with alkaline water and control group with alkaline water). DNA was extracted from individual bacterial reference strains and from faecal samples using a modified faecal extraction DNA method and then amplified by PCR and the quality of each bacterial DNA extracted was checked. Real-time PCR assays were used for quantification of the target bacterial DNA from faecal DNA preparations. SCFFAs relative content was determined by solid phase microextraction - gas chromatography. Results: Gut rat microbiota was affected one month after PERM treatment, but after two months no significant changes in the bacteria composition were observed between control and PERM group. The alkaline water do not induce any change in the microbiota of treated rats. Also the SCFFAs relative content revealed significant differences between the control and the treated group only one month after PERM treatment. Conclusions: Further studies are necessary to analyze the effect of alkaline water on rat gut microbiota composition, prolonging the time of treatment with alkaline water until adult and old age of animals.